Golf clubs are formed through a variety of methods. Commonly, a golf club head is forged or cast and then machined to the requisite dimensions and desired aesthetic quality. These processes have proven to be time consuming, inefficient, and expensive.
Recently, powdered injection molding has come to the forefront of golf club manufacturing. Metal injection molding or (MIM) is a manufacturing process which combines the versatility of plastic injection molding with the strength and integrity of machined, pressed or otherwise manufactured small, complex, metal parts. The process generally involves combining fine metal powders of a diameter of less than 45 micrometers with plastic binders (various thermoplastics, waxes, and other materials), which allow the metal to be injected into a mold using standard plastic injection molding machines.
After the part is molded and before the binders are removed, the post molding product is referred to as a “green part.” The next step is to remove the binders and flow agents with solvents and thermal processes. The resultant metal part is then sintered at temperatures great enough to bind the particles but not melt the metal. This process results in a golf club that has a crisp, clean appearance similar to a golf club subjected to a milling process. However, this process requires powdered metals, which are expensive.
For example, U.S. Pat. No. 6,478,842 generally discloses a unitary golf club head made by metal injection molding. This requires that the entire volume of the club head is formed from powdered metal, which, as mentioned above, is cost prohibitive based on the cost of powdered metals.
Therefore, what is needed is a golf club that can be produced efficiently and with a low volume of powdered metal, while maintaining performance characteristics and aesthetic quality.